1) Syncs hosts time via timesync command.
2) After first boot of vms test check time on vms
   if time difference from host is greater than
   time_diff_limit it writes warning to log.
3) Migrates machine between hosts and compares
   time differences on hosts and guests after migration.
  - If difference is greater than time_diff_limit raise error.
Signed-off-by: NJiří Župka <jzupka@redhat.com>